The joining ceramic SiC and composite Al2O3-SiC to metals
Władysław Włosiński, Wiesłąwa Olesińska, Andrzej Jagoda Instytut Technologii Materiałów Elektronicznych, ul. Wólczyńska 133, 01-919 Warszawa
Annals 4 No. 12, 2004 pages 363-368
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abstract The paper presents the results of studies on joining SiC ceramics and Al2O3-SiC with the ceramic surface being activated by titanium, chromium or copper. Titanium and chromium were deposited by the sputtering technique, and copper - by the electrochemical method. The microstructures of the SiC/Mo and Al2O3-SiC/FeNi42 joints brazed with the CuMn12Ni3 solder and copper in a nitrogen atmosphere were examined and the results discussed. The presented paper includes the results: - diffraction pattern of sintered layers (Tab. 1, Fig. 1), - microstructures of the joints SiC/Mo and Al2O3-SiC/FeNi42 (Figs. 3-5, 7), - mechanical strength of the joints (Tab. 2, Fig. 6). The joints, in which the ceramic surface was activated in addition with chromium, do not contain mechanical defects caused by the joining process, and the ceramic surface is covered with a continuous layer of the solder. A phase analysis of the interface surface identified a MeSiC phase. The lowest number of new phases was observed in the case of SiC ceramics with chromium and titanium layers. Besides TiC, Ti3SiC2 and Cr2C phases were identified. The amount of the new dispersive phases is rising in the presence of manganese. High mechanical strength was obtained only for joints with the layers containing chromium and titanium. SiC/Mo and Al2O3-SiC/FeNi42 joints soldered by the layers with chromium and titanium have continues and compact microstructures on all the length of the joint. There was obtained a barrier layer in the SiC ceramics (Fig. 2). The thickness of the barrier of Ti3SiC2 was about 1 μm. The ternary of Ti3SiC2 compound shows a combination of properties that is unparalleled among ceramic materials (Fig. 9). In the joining processes, it is advantageous when the interface formed on the ceramics contains high plasticity phases, since they enable relaxing the thermal stresses generated when joining the materials with greatly differing thermal properties. There were no new phases on the surface of composite ceramics. The surface with a chromium layer was wetted very well by the solder, which was similar to the behaviour of silicon nitride ceramics (Fig. 8). For electronic application the mechanical strength of the joints is sufficient. Key words: ceramic coatings, joining SiC/Mo and Al2O3-SiC/FeNi42, active metal braze